Liner for grinding mills

ABSTRACT

A grinding mill having an inner liner assembly which comprises a plurality of spaced guide members secured to the inner peripheral surface of the grinding mill thus forming rows of guide members extending longitudinally of the axis of rotation of the grinding mill; a liner member disposed between each row of guide members forming liner rows adjacent to and along the length of the guide members; lifter members coincident with the guide members and slidably engaged therewith along the length of the guide members to substantially overlie and edge portion of the adjacent liner rows thus forming rows of lifter members alternately disposed with the liner rows; and key lifter members secured to the inner surface of the grinding mill to maintain the alternate rows of the lifter members and the liner members in their respective positions.

United States Patent Russell 3,820,727 June 28, 1974 LINER FOR GRINDING MILLS Primary Emminer-Granvillc Y. Custer, Jr. Assistant Examiner-Howard N. Goldberg inventor: Robe" Jackson Russell York Attorney, Agent, or Firm-Olin E. Williams; Oscar B.

Brumbach; Boyce C. Dent 73 Assignee: Koppers Company Inc., Pittsburgh,

[57] ABSTRACT A grinding mill having an inner liner assembly which comprises a plurality of spaced guide members se- [22} Filed: Nov. 10, 1972 [21] Appl. No.: 305,435

cured to the inner peripheral surface of the grinding mill thus forming rows of guide members extendinglongitudinally of the axis of rotation of the grinding mill; a liner member disposed between each row of guide members forming liner rows adjacent to and 929 9H9 Q7 11L 4 2km 0 %B3 1 m U m 4 2 WM mmh "c r mum L mf C d nUIF lll. Z oo 555 [56] References Cited along the length of the guide members; lifter members UNITED STATES PATENTS coincident with the guide members and slidably engaged therewith along the length of the guide mem- 3,211,387 10/!965 Russell et 24l/l83 X 3,580,520 5/|97| 241/299 berg K0 substamlally overlie and edge p n Of the 3,582,007 6/!971 Heighberger...................... 241/183 adjacent liner rows thus forming rows of lifter mem- 3,604,637 9/1971 Sabaski........................... 241/181 X bcrs alternately disposed with the liner rows; and key FOREIGN PATENTS OR APPLICATIONS lifter members secured to the inner surface of the grinding mill to maintain the alternate rows of the 680,0l2 lifter bers an the liner m r n their e pec tive positions.

4 Claims, 6 Drawing Figures PME N'TEUJum IBM 3.820.727

sum 2 or 2 lirllrjrjibrl LINER FOR GRINDING MILLS CROSS REFERENCE TO RELATED APPLICATIONS This invention relates to the grinding mill structure disclosed in co-pending application Ser. No. 222,935 filed on Feb. 2, 1972 by Wolfram J. Mix entitled Method and Apparatus for Lining a Grinding Mill, and assigned to the assignee of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to solid material comminution by contact between relatively moving portions of material and more particularly to the securing of wear liner assemblies to the inner periphery of grinding mills.

2. Description of the Prior Art Grinding mills generally utilize a substantially cylindrical shell made of heavy steel plate. Crude ore is fed into the shell for processing and the shell is continuously rotated until the ore is reduced to a desired size. Various types of mills utilize rods, tubes and balls as media to aid in the grinding of the crude ores. Other mills utilize the autogenous grinding method wherein the ore is its own grinding media, or semi-autogenous method wherein a mixture of ore and steel charge is used as the grinding media.

Grinding mill shells must be able to withstand continuous impacts and abrasion caused by movement of the ore within the rotating shell. To move the ore and protect the steel shell, the inner peripheral surface of the mill shell is usually lined with a hardened liner assembly. Generally, liner assemblies comprise a plurality of substantially flat liner members on the inner surface of the shell between which rows of lifter members are also bolted to the shell. Sometimes the liner members are bolted directly to the shell and have raised rib portions on their work surfaces thus excluding the need for separate lifter members. The liner members protect the shell of the mill and the ribs or lifter members lift the ore toward the top of the rotating shell to a point where gravity causes the ore to tumble toward the bottom of the shell where it is reduced in size by impact with pieces of ore or with the liner and lifter members. In

mills using grinding media, as previously mentioned,

the lifter members tend to lift the grinding media in the same manner described for the ore. Thus, the grinding media also tumbles toward the bottom of the shell and impacts against the ore.

Therefore, it can be seen that liner assemblies are exposed to continuous high impact loads and abrasion during normaloperation which wears out the liners. Thus, periodic replacement of the liner or portions thereof is required.

Liner assemblies are customarily bolted to the inner peripheral surface of the mill shell by bolts extending from inside the mill, passing through the liners or lifters and then through the shell. The bolts are secured by nuts tightened against packing washers and steel washers prevent leakage of ore fines through the shell. lndividual sections of liners and lifter members are bolted to the shell and generally extend over the entire inner surface including portions of the ends or heads of the shell. As a result, a large number of bolts are required to secure a liner assembly in place. In addition to the expense of replacing broken bolts and the problem of leakage through bolt holes in the shell, the use of such a large number of bolts requires considerable down time when liner sections are to be replaced. Each individual bolt must be re-installed to secure the new liner sections in place.

Continuous impact of the ore against the linings often causes the bolts to fret in the holes and sometimes elongates the holes. Leakage of ore tines may occur and eventually it may be necessary to drill the holes oversize and put bushings in them so that the bolts are effective in securing the liner sections to the shell.

Lifter members also tend to overturn from the forces of heavy impact of the ore against them. Such forces induce tensile and bending moments in the bolts securing the members against the shell; the bolts sometimes elongate or shear resulting in loose lifters; as the bolts elongate or bend, the entire liner assembly may shift thereby making replacement of the liner assembly particularly CliffiCUlt.

Another problem is that the exterior of the entire mill is often inaccessible since mills are sometimes mounted high above the ground or even partially in pits. It is difficult to rotate large mills and stop them exactly where the bolts and nuts will be accessible for replacement. Therefore, for these and other reasons it is advantageous to be able to replace the liner assembly completely from within the mill.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a grinding mill liner assembly that will overcome the aforementioned disadvantages and others. Thus, this invention provides liner assemblies for grinding mills which are capable of being removed and replaced within the grinding mill with a minimum amount of bolt or screw removal.

This is generally accomplished by providing a grinding mill with a liner assembly which comprises a plurality of spaced guide means secured to the inner peripheral surface of the grinding mill thereby forming rows of the guide means extending longitudinally of the axis of rotation of the mill; a liner means disposed between the rows of the guide means form liner rows adjacent to and along the length of each of the guide means; a lifter means coincident with each of the guide means and slidably engaged therewith along the length of the guide means to substantially overlie an edge portion of each of the adjacent liner rows thus forming rows of the lifter means alternately disposed with the liner rows; and a key lifter means secured to the inner surface of the grinding mill to maintain the alternate rows of the lifter means in their respective positions.

The above and further objects and novel features of the invention will appear more fully from the following detailed description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are not intended as a definition of the invention but are for the purpose of illustration only.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings wherein like parts are marked alike:

FIG. 1 is a side elevation in partial cross-section of a grinding mill generally illustrating the liner assembly of the present invention secured to the inner periphery of the shell, including the ends of the shell;

FIG. 2 is a partial end view of the mill taken along the line IIII of FIG. 1 illustrating the interior of the discharge end of the mill and the radial convergence of the liners and lifters of the lining assembly in the end of the mill;

FIG. 3 is an enlarged side elevation in partial crosssection of the-lower half of the grinding mill shell of FIG. 1 showing the novel liner assembly of the present invention;

FIG. 4 is an enlarged axial section of a portion of the outer periphery of the shell taken along line IVIV of FIG. 3 illustrating the engagement of the lifter means with the guide means with the liners disposed between adjacent lifter means; 7

FIG. 5 is an enlarged axial section of a portion of the outer periphery of the shell taken along line VV of FIG. 3 illustrating the engagement of the key lifter means with the liners and the method of attachment of the key lifter means to the shell; and

FIG. 6 is an enlarged axial section of a portion of the outer periphery of the shell showing an alternate embodiment of the key lifter means of the present inventron.

DESCRIPTION OF THE PREFERRED EMBODIMENT The liner assembly of the present invention is shown in connection with an autogenous grinding mill generally noted as numeral 10, in FIGS. 1 and 2. The mill includes a shell generally noted as numeral 12 which includes a cylindrical shell portion 14 and a radially tapering feed end portion 16 and a similar discharge end portion 18. Each of the ends 16 and 18 include a trunnion 20 and 22 respectively which supports the mill for rotation in bearings (not shown) in the conventional manner. Feed end 16 includes a stationary feed chute 24 supported outside the mill (supports not shown) extending within trunnion through which ore is introduced into the interior of mill 10 along a feed cone 26 secured to trunnion 20. The discharge end 18 includes a grate 28 spaced from the end of shell 18 to provide a space 30 for receiving ore fines for discharge out of mill 10 through the inside of cone 32 secured inside of trunnion 22. Cone 34 defines the inner periphery of the space 30 adjacent discharge cone 32.

A liner assembly generally noted as numeral 36 covers substantially the entire interior surface of shell 12 except for the feed cone 26 and cone 34. The profile of the liner assembly 36 is preferably made as shown in the cutaway portion of FIG. 1. The liner elements are preferably made from short straight bars and plates as shown in FIGS. 1 and 2 since they are more easily installed than longer sections extending the full length of the shell.

Generally, as illustrated in FIG. 3, liner assembly 36 comprises a plurality of spaced guide members 38 secured to the inner peripheral surface 40 of shell 14 such as by bolting (not shown) or more preferably such as by a weld 68 (FIG. 4), thereby forming rows of guide members 38 extending longitudinally of the axis of rotation of mill 10. A liner member 42 is disposed between each row of guide member 38 forming liner rows adjacent to and along the length of each guide member 38. Cylinder and head lifter members 44 which are coincident with each guide member 38 and slidably engaged therewith along the length of each guide member 38 substantially overlies and edge portion of each of the adjacent liner rows thus forming rows of lifter members 44 alternately disposed with the liner rows.

Guide members 38 have a gap or discontinuation 46, which has at least the equivalent length of a lifter member 44 located at a convenient place along the length of each guide member 38 to permit lifter members 44 to be removed and replaced from their respective lifter member row. Key lifter members 48 are placed coincidently along the lifter member rows where gap 46 occurs. Key lifter members 48 are secured in place to the inner peripheral surface 40 of shell 14 such as by bolts 49 placed through bolt holes 50, thus maintaining the alternate rows of lifter members 44 and liner members 42 in their respective positions.

Similar guide members, liner members, lifter members, and key lifter members are likewise secured to ends 16 and 18 of shell 12. For example, as best illustrated in FIG. 2, longitudinally substantially abutting lifter segments form head lifter members 44 extending from cylinder lifter members 44 on the cylindrical shell 14 toward cone 34. The liner members comprise arcuate segments disposed between head lifter members 44. Thus, one liner member 54 extends between head lifter members 44. Other liner segments 56 extends between head lifter members 44. Other liner segments 58 also extend between head lifter members 44. The entire surface of ends 16 and 18 are covered by the liner members, however, on discharge end 18, the outermost liners 54 and 56 include slots 60 to form grate 28 (FIG. 3) to permit ore fines to pass into space 30 (FIG. 3) for discharge through cone 32.

More specifically, as shown in FIG. 3, guide members 38 are provided on cylindrical shell 14 and on both ends 16 and 18 of grinding mill 10. Guide members 38 are provided in a spaced relationship about the inner peripheral surface 40 of mill 10 in such manner that each guide member 38 is co-planar with a radius struck from the axis of rotation of mill 10. This arrangement results in equally spaced guide members 38 on the inner peripheral surface 40 of cylindrical shell 14 and converging guide members 38 on the inner peripheral surface 40 of ends 16 and 18. As shown in FIG. 4 guide members 38 are shown having a T shaped crosssection including rib portions 62 which are secured to the inner peripheral surface 40 of cylindrical shell 14 and to the inner peripheral surface 40 of ends 16 and 18 such as by a weld 68 or by any other suitable means; and flange portions 64 which are provided to accommodate similarly shaped slots 66 in lifter members 44. Although the above construction of guide members 38 is the preferred method of construction, it should be understood that other shaped guide members may also be utilized, such as Y shaped, V shaped, and any other properly shaped guide members (not shown). Any shaped guide member may be utilized as long as the slots in the lifter members corresponds to the shape of the guide members, and the shape is such that the lifter members will be securely held in place when engaged with the guide members. With T shaped guide members 38 and with correspondingly shaped slots 66 in lifter members 44, lifter members 44 are slidably engaged along the length of guide members 38. As shown in FIG. 3, each guide member 38 has a gap or discontinuation 46 along its length which is at least equivalent to the length of lifter members 44. In this manner each lifter member 44 is placed in position coincident with its respective guide member 38 and is slidably moved along the length of each guide member 38 which is engaged by slot 66 (FIG. 4) of each lifter member 44.

Successive lifter members 44 are similarly added along guide members 38 until a row of lifter members is complete. When a substantially long guide member 38 is required, such as is used in a large grinding mill, :1 gap 46 may be provided at either end of guide members 38 (not shown) or at any convenient point between the ends of guide members 38 (not shown). Preferably, the location of gap 46 is placed to provide the most expedient access for the removal and replacement of lifter members 44.

Referring to FIG. 4, liner members 44 are placed end-to-end in substantially abutting relationship adjacent to and along the length of guide members 38 thus forming liner rows disposed between the spaced guide members 38. Liner members 42 are of equal width when used in cylindrical shell 14, but have tapered widths corresponding to the converging guide members provided along ends 16 and 18. Liner members 42 are provided with tapered edge portions 70 adjacent ribs 62 of guide members 38. When all liner members 42 are positioned about inner peripheral surface 40 of cylindrical shell 14 and ends 16 and 18 the result is a discontinuous raised protective surface about cylindrical shell 14 and ends 16 and 18 with respect to inner peripheral surface 40 thus providing the needed protection for grinding mill 10. Each guide member 38 with its adjacent liner member rows having tapered edge portions 70 provide a path for lifter members 44 which are slidably moved along the length of guide members 38.

Lifter members 44, when positioned about inner peripheral surface 40, provide a discontinuous raised surface about cylindrical shell 14 and ends 16 and 18 with respect to the surface formed by liner members 42. It should be understood, however, that the discontinuous surfaces provided by liner members 42 and lifter members 44 actually provide a substantially continuous sur face of varying height about the inner peripheral sur face 40 of grinding mill l0.

The tapered path formed by each guide member 38 and the tapered edge portions 70 of adjacent rows of liner members 42, accommodates lifter members 44 having slots 66 corresponding in cross-section to guide members 38 and a tapered portion 72 which corresponds to the similarly tapered edge portions 70 of liner members 42. Lifter members 44 are positioned in gap 46 (FIG. 3) of guide members 38 and then slidably moved along guide members 38 as previously described. Successive lifter members 44 are similarly placed along guide members 38 until each guide member 38 is completely engaged by a row of lifter members 44. With this arrangement the rows of lifter members 44 with tapered edge portions 72 overlie tapered edgeportions 70 ofthe adjacent rows of liner members Referring now to FIG. 5,key lifter members 48 are positioned coaxially with each row of lifter members in each gap 46 to secure the liner assembly 36 (FIG. 3) in place. Key lifter members 48 and lifter members 44 are substantially the same size and shape except that key lifter members 48 are not provided with slots as are lifter members 44 and therefore do not engage guide members 38. Since the key lifter members 48 do not contain slots, they are positioned in each lifter member row where gap 46 (FIG. 3) occurs in each guide member 38. Therefore, with each gap 46 being of substantially equivalent length to lifter members 44 and key lifter member 48, the positioning of a key lifter member 48 in coaxial alignment with each row of lifter members 44 will complete a lifter member row. Key lifter members 48 are provided with bolt holes 50 preferably placed side-byside across the width of key lifter members 48 to seat key lifter members 48 firmly in position and to provide greater resistance of key lifter member 48 to the shear forces produced when the rotating mill moves the ore andthe grinding media which have a tendency to remain at rest. In addition, keyv lifter members 48 have tapered edge portions 74 adaptable to coincide with tapered edge portions of liner members 42. Bolts 49 are placed in bolt holes 50 and secured to inner peripheral surface 40 thereby securing key lifter members 48 in its appropriate lifter member row. Since lifter members 44 are only slidably movable along guide members 38, and since each row of lifter members 44 overlies tapered edge portions 70 of its adjacent rows of liner members 42, the liner members 42 are likewise secured in position. With this arrangement, the entire liner assembly 36 (FIG. 3) is secured about inner peripheral surface 40 with a minimum number of bolts 49 required since bolts 49 are only used to secure key lifter members 48 to the inner peripheral surface 40 of grinding mill 10.

FIG. 6 illustrates an alternate arrangement to the key lifter members when it is determined that the preferred key lifter member 48 (FIG. 5) would not be suitable because a different type or configuration of mill is to be used or where the ore to be gound is of such a size and shape that the possibility of overturning lifter members 44 may occur. The alternate key lifter member is a unitary key lifter member 76 which corresponds substantially to two lifter members disposed in a side-by-side relationship separated by an interconnecting liner member 78. When a unitary key lifter member 76 is used it replaces the equivalent ofa liner member 42 and two adjacent key lifter members 50, (FIG. 5). The unitary key lifter member 76, due: to its extreme width, has substantial resistance to overturning as compared to lifter members heretofore known. Only a single bolt 81 is needed in each unitary key lifter members 76 extension portion 80 as provided for by single bolt holes 82, since the resistance to overturning is increased by the extreme width of unitary key lifter member 76. Each unitary key lifter member 76 is adaptable to be secured by bolts 81 through bolt holes 82 to the inner peripheral surface 40 of grinding mill l0, and are coincidental with alternate rows of liner members 42 and their respectively adjacent rows of lifter members 44.

In operation, guide members 38, lifter members 44, liner members 42, and key lifter members 48 form an interlocking protective liner assembly 36 about the inner peripheral surface 40 of grinding mill 10. Key lifter members 48 are the only members of liner assembly 36 secured by bolts 49 to inner peripheral surface 40. Lifter members 44 are only slidably movable along guide members 38 and therefore cannot be moved until a particular key lifter member 48 is removed. Each row of lifter members 44 and key lifter members 48 overlies tapered edge portions 70 of adjacent rows of liner members 42 thus maintaining liner members 42 position.

When it becomes necessary to change or replace a particular member of liner assembly 36 the appropriate key lifter member 48 is removed from the desired row of lifter members 44 by removing the bolts 49 which secures the particular key lifter member 48 in place. Thus gap portion 46 of the respective guide members 38 is exposed and lifter members 44 of the respective row may be successively removed until all or only the desired ones are removed. One-by-one each lifter member 44 is slidably moved along guide member 38 until the lifter member 44 disengages from guide member 38 as lifter member 44 reaches gap 46. The lifter member 44 may then be lifted out of gap 46. When all or the desired ones of lifter members 44 are removed as previously described liner members 42 may be removed from the liner rows adjacent to the lifter members 44 and their respective guide members 38. Thus the removal of a row of lifter members 44 expose its two adjacent rows of liner members 42. When the desired lifter members 44 and liner members 42 are removed, new lifter members 44 and liner members 42 replace the worn or damaged members as desired, and the key lifter member 48 is replaced in gap 46 and se cured by bolts 49 to inner peripheral surface 40.

Thus. a grinding mill is provided with a liner assembly with alternate rows of lifter members and liner members secured by rows of guide members in which each guide member has at least one key lifter member secured by bolts to the inner peripheral surface of the grinding mill. The result is as interlocking and overlapping liner assembly which provides an expedient method for the replacement of desired portions thereof without requiring the use of or need for a substantially large number of bolts.

Thus, the invention having been described in its best embodiment and mode of operation, that which is desired to be claimed by Letters Patent is:

l. A grinding mill having an inner liner assembly comprising:

a plurality of spaced guide means secured to the inner peripheral surface of said mill thereby forming rows of said guide means extending longitudinally of the axis of rotation of said mill;

a liner means disposed between said rows of said guide means forming liner rows adjacent to and along the length of each of said guide means;

a lifter means coincident with each of said guide means and slidably engaged therewith along the length of said guide means to substantially overlie an edge portion of each of said adjacent liner rows thus forming rows of said lifter means alternately disposed with said liner rows; and

a key lifter means secured to said inner peripheral surface of said mill coaxially aligned with at least one of said rows of said lifter means and out of engagement with said guide means for maintaining said alternate rows of said lifter means and said liner means in their respective positions.

2. The liner assembly of claim 1 wherein:

each row of said guide means includes at least one T shaped member with the base of the leg of said T" shaped member secured to said inner peripheral surface of said mill; and

each row of said lifter means includes a T shaped slot adapted for sliding engagement longitudinally along said Tshaped guide means.

3. The liner assembly of claim ll wherein a selected one of said key lifter means may be removed from its respective lifter means row thus permitting the subsequent successive removal of said lifter means and said liner means.

4. The liner assembly of claim 1 wherein said key lifter means comprises:

a unitary key lifter means corresponding substantially in cross-section to two of said lifter members disposed in a side-by-side relationship and separated by an interconnecting liner means;

each of said unitary key lifter means being secured to said inner peripheral surface of said mill coaxially with alternates of said rows of said liner means and their respectively adjacent said lifter means and out of engagement with said guide means thereby maintaining said alternate rows of said lifter means and said liner means in their respective positions. 

1. A grinding mill having an inner liner assembly comprising: a plurality of spaced guide means secured to the inner peripheral surface of said mill thereby forming rows of said guide means extending longitudinally of the axis of rotation of said mill; a liner means disposed between said rows of said guide means forming liner rows aDjacent to and along the length of each of said guide means; a lifter means coincident with each of said guide means and slidably engaged therewith along the length of said guide means to substantially overlie an edge portion of each of said adjacent liner rows thus forming rows of said lifter means alternately disposed with said liner rows; and a key lifter means secured to said inner peripheral surface of said mill coaxially aligned with at least one of said rows of said lifter means and out of engagement with said guide means for maintaining said alternate rows of said lifter means and said liner means in their respective positions.
 2. The liner assembly of claim 1 wherein: each row of said guide means includes at least one ''''T'''' shaped member with the base of the leg of said ''''T'''' shaped member secured to said inner peripheral surface of said mill; and each row of said lifter means includes a ''''T'''' shaped slot adapted for sliding engagement longitudinally along said ''''T''''shaped guide means.
 3. The liner assembly of claim 1 wherein a selected one of said key lifter means may be removed from its respective lifter means row thus permitting the subsequent successive removal of said lifter means and said liner means.
 4. The liner assembly of claim 1 wherein said key lifter means comprises: a unitary key lifter means corresponding substantially in cross-section to two of said lifter members disposed in a side-by-side relationship and separated by an interconnecting liner means; each of said unitary key lifter means being secured to said inner peripheral surface of said mill coaxially with alternates of said rows of said liner means and their respectively adjacent said lifter means and out of engagement with said guide means thereby maintaining said alternate rows of said lifter means and said liner means in their respective positions. 